Add AI translation for comments and video descriptions

Comments get a Translate button that calls the active LLM provider in Admin → AI
settings. Each commenter shows a small country flag inferred from their
video_views + profile_visits history (falls back to users.nationality); that
inferred country drives the language hint passed to the LLM so Portuguese
"Linda, linda, linda" translates to "Beautiful" instead of pass-through.

Description boxes get a line-paired translation grid: a shared Translate button
flips #vdbDescSplit into a two-column CSS grid where every source line sits
next to its translation on the same row. Backend splits by newline and asks
the LLM for a JSON map keyed by index so counts always match.

LlmLyricsService now has translate() + translateLines() with echo-retry (if the
model returns the input unchanged while source != target, retry once with a
stronger directive) and keeps the Ollama model resident via keep_alive=1h.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

app/Http/Controllers/CommentController.php

@@ -8,6 +8,7 @@ use App\Models\Video;
 use App\Notifications\NewCommentLikeNotification;
 use App\Notifications\NewCommentNotification;
 use App\Notifications\NewReplyNotification;
+use App\Services\LlmLyricsService;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Auth;
 
@@ -15,7 +16,7 @@ class CommentController extends Controller
 {
     public function __construct()
     {
-        $this->middleware('auth')->except(['index']);
+        $this->middleware('auth')->except(['index', 'translate']);
     }
 
     public function index(Video $video)
@@ -34,6 +35,29 @@ class CommentController extends Controller
 
         $commenter = Auth::user();
 
+        // Idempotency guard: a client that retries (duplicate listeners after an
+        // SPA swap, fast double-click, a flaky connection) can POST the identical
+        // body twice. Treat an identical comment from the same user to the same
+        // video within 5 seconds as the same submission and return the first one.
+        $existing = $video->comments()
+            ->where('user_id', $commenter->id)
+            ->where('body', $request->body)
+            ->where(function ($q) use ($request) {
+                $request->parent_id
+                    ? $q->where('parent_id', $request->parent_id)
+                    : $q->whereNull('parent_id');
+            })
+            ->where('created_at', '>=', now()->subSeconds(5))
+            ->latest('id')
+            ->first();
+
+        if ($existing) {
+            return response()->json([
+                'success' => true,
+                'comment' => $existing->load('user:id,name,avatar'),
+            ]);
+        }
+
         $comment = $video->comments()->create([
             'user_id'   => $commenter->id,
             'body'      => $request->body,
@@ -89,6 +113,37 @@ class CommentController extends Controller
         return response()->json(['success' => true]);
     }
 
+    public function translate(Request $request, Comment $comment, LlmLyricsService $llm)
+    {
+        if (! $llm->isEnabled()) {
+            return response()->json(['error' => 'Translation is not configured'], 503);
+        }
+
+        $target = (string) $request->input('target', 'en');
+
+        // Derive a source-language hint from the comment author's most-frequent
+        // access country (video_views + profile_visits, falling back to their
+        // nationality setting). Never trust the client for this — it's used
+        // to disambiguate scripts the LLM might otherwise misidentify.
+        $topCountries = \App\Models\User::topCountriesFor([$comment->user_id]);
+        $sourceCountry = $topCountries[$comment->user_id] ?? null;
+        $sourceLang    = \App\Data\CountryLanguages::primary($sourceCountry);
+
+        $translated = $llm->translate((string) $comment->body, $target, $sourceLang);
+
+        if ($translated === '') {
+            return response()->json(['error' => 'Translation failed'], 502);
+        }
+
+        return response()->json([
+            'success'       => true,
+            'translated'    => $translated,
+            'target'        => $target,
+            'source_hint'   => $sourceLang,
+            'author_country'=> $sourceCountry,
+        ]);
+    }
+
     public function like(Comment $comment)
     {
         $userId  = Auth::id();